What format is the captured file? If by "dvc" you mean digital video camera, then it was probably captured as a DV .avi file which is compressed about 5:1. Uncompressed .AVI is much larger. It should be about 5 times larger than the captured file, so there is probably something else besides this going on too.

YOur DVC is compressed video file, uncompressed will always be bigger. Similar to a normal audio file (wav) vs. an MP3 file.

Dave T2

So, the information on my camera is already compressed? This raises another question then: how is it possible to make copies of tapes without loss of quality? I mean, don't I loose something each time I recapture and re-render, even though I'm not doing any further editing? Is there some other way to make a copy of a tape that doesn't involve capture and render?

I don't know what camera you have, but this is the normal procedure for DV or Digital 8.

When you capture your footage from the camera, you are actually doing a data transfer. There is no compressing or recompressing involved. When you output to your camera, the same thing. Just like copying a file.

The only time the file is uncompressed/recompressed is when you add effx such as titles or dissolves. Most of the time, there is only a minimal change in quality. But that might be dependent upon the actual DV codec used. Some people think that the Sonic Foundry codec is better than the MS codec.

So if you capture your footage, and do nothing but cuts, ordinarily the file is unchanged and the quality stays the same as the original camera tapes. Unlse you render to another format, such as MPEG or QT. Then the footage is uncompressed and recompressed and there is usually a change in quality.

Dave T2

I appreciate the help, but I'm still a bit confused. My camera is a Sony Digital 8 (DCR-TRV340 NTSC). I just did another experiment. When I captured a one minute (1:00:11) clip it says ".avi" under the clip. And the file is 220.29mb. I do nothing other than place the clip on the timeline and open "make movie." If I choose NTSC DV as the template to render to .avi, in order to print to tape, the file is about the same size, slightly larger, whereas choosing "default template (uncompressed)" results in a 2.45gb file.

Is my captured file, the one I'm looking at on the timeline in a compressed state? And was it already in this state on my camera? Is that what Chienworks means about DV being compressed 5:1? That is, is my 220.29mb file just a compressed file that would be 2.45gb if it weren't compressed? So, choosing the NTSC template is simply maitaining the same level of compression, while choosing the "default template" is actually uncompressing the file?

If that is true, then I guess that leads me to one more question. Why does the camera compress in the first place? So people could manage files on their computers?

Your assessment is completely correct. The camera compresses the data to begin with ... well, to be compatible with the DV standard which is compressed. At the time DV was introduced, cameras, tapes, and computers couldn't store enough information fast enough to work with uncompressed. Remember, DV camcorders first came out when 486SX computers were the norm for most folks and no one had even heard of a hard drive bigger than 310MB.

Ok, thanks. That clears up my confusion. So, just out of curiosity, is there anything to be gained by rendering to uncompressed .avi? Also, are there now DV cameras that do not compress the data?

You only gain by using uncompressed if you are planning on editing with uncompressed. In this way there is no recompression during rendering processes, so there is no quality changes. Of course, you have to be able to handle large file sizes as you figured out.

As Chienworks said, compression is an attempt to get as much information as possible in as little tape/time/storage as possible. MP3's are an example of high lossy compression. To a lot of people, the quality is as good as an uncompressed audio track, and as such accept the standard because of its file size.

Few consumer formats use uncompressed. You generally will find uncompressed in professional broadcast situtations. And compared to VHS, which is uncompressed, most digital cameras look much better.

Some professional standards use compression such as Digital Betacam. But the hardware and compression algorithms are higher quality than most consumer devices.

Dave T3

All very interesting, but is DVavi compression lossy?

DV is slightly lossy, but the loss is almost unnoticeable. Probably about the only time it's really obvious is when you have fast motion around dark red areas (mostly due to the 4:1:1 compression).

Our local TV station, WRGB, is ditching all their betacam equipment for DV, so i guess the pros feel it's acceptable enough.